Seriously, when your name gets that big it's not those who try to use your name that you have to worry about long term... It's the misinformation of terms and improper use of trademarks that lead to a trademark going the way of a genericized trademark. That is what you need to look out for. Those kinds of improper uses to get your trademark higher recognition for many a registered trademark has signaled the beginning of the end.
Flash = strobe; Strobe = flash; It doesn't even matter if it's true or not if that is what the masses believe. You can make it your personal life goal to educate them back to what is the truth, but I am telling you 100% completion of that task will be a failing mission. It's like a virus. Depending on where you call home the courts may very well side with what the uninformed masses know to be incorrectly true as well.
Those companies that are large enough and smart enough to be able monitor this and fight this ahead of time are better off of course. Even then it is still some what out of their hands and part of the cost of having high market dominance. When your trademark name no longer indicates who makes the product but instead to the masses transforms into your product or service itself you have a much harder fight to win.
I say now is the time for him to fight of course, if it is not already to late. Best of luck to him as that will indeed play some part to his hopeful story of success.
The below listed are just a small taste of some genericized trademarks:
The sony Walkman, Rollerblades, Kleenex, Band-Aid, Lego, escalator, aspirin, Scotch Tape, Cellophane, Dry ice, Escalator, Heroin, Hoover, Kerosene, Linoleum, Mimeograph, Netbook, Petrol, Pilates, Thermos, Touch-tone, Trampoline, Videotape, Webster's Dictionary, Yo-Yo, Zipper
Some have fallen, some still stand, some it depends on where you are located. But be assured bigger names then the Strobist have fought and lost. With the way I see it going as time continues on I would not be surprised if his fight just keeps getting harder and harder. At least for now he can be somewhat reassured that at least the term "strobist" has not found it's way into the common dictionary. ...but for how long?
Just how I see it from where I sit.